Sandblast apparatus



March v3o, 1937. E, AUgFE-R 2,075,732

SANDBLAST APPARATUS Fi'ld May as, 1935 H312/ S y A Patented Mar. 30, 1937 j@ IoNrrsosiirrf.v -:s PATENT ori-lcs Emile Lauffer, Liege, Belgium Application May 1s, 1935, seria1No. 21,266

` In Belgium May 19, 1934 1 Claim.

This invention has reference to sand blast apparatus, in which sand is drawn away by means of compressed air in order to obtain a stream capable of cleansing machine parts or 5 realizing any other industrial use.

In the well known apparatus of this type, the sand contained in a receptacle under pressure runs into a mixing chamber into which the compressed air flows by creating generally eddies and whirls, which prevent to obtain a regular sand stream and necessitate a too large consumption of compressed air.

In order to avoid this inconvenience, accordl ing to the present invention, the sand is conducted into a space of the mixing chamber, which is not affected by the airstream in such a way as to be drawn into the air being relatively expended, and then to be expelled from this chamber without formation of eddies. A particularly convenient method of carrying out the invention consists in terminating the air pipe in the mixing chamber according to the Vertical axis of the sand outlet passage and in causing the divergent air stream to attain the walls of the mixing chamber at the points where begins a frusto conical duct forming part of said chamber and connected to the sand delivery pipe; thus the sand is mixed to the air stream in a homogeneous manner and remains in this condition until it leaves the delivery pipe.r In

order further to avoid the formation oi a deposit of sand in the bottom of the mixing chamber, the lower wall of said chamber is made tangent to the divergent stream of air, which escapes from the air nozzle. Other novel fea tures of the invention will be apparent in the claims and the description of the accompanying drawing in which:

Figure 1 is an elevation View; 4,0 Figure 2 is another elevation view with a longitudinal section in the mixing chamber.

On a tripod I is secured in a most convenient way a cylindrical metal receptacle 2 provided inwardly at a determined height with a discharge hopper 3 receiving the sand and closed at its bottom by means of an automatic valve ll. The valve l is carried in a sliding way through a pipe 5 terminated externally by a three-way cock 6, to which are connected the air pipes 1 and 8, the first thereof being in relation with an air compressor, and the second leading to a mixing chamber I5, situated under the conical bottom I0 of the receptacle 2, the inner space oi the latter being connected to the pipe 8, un-

der the cock 6 by a pipe II.

The three-way cock 6 is operated by means of a handle I2 arranged at the same side of the receptacle 2 as the lever I3 actuating upon the sand distributor, so that the operator can easily reach the two supply organs. 5

'I'he bottom I0 of the receptacle 2 is centrally provided with a passage I4 connecting the receptacle with the mixing chamber l5, com. posed of two crusto conical sections joined at their large bases and forming a frusto-conical 10 nozzle I6, which is aflixed to a chest I1 carried by the bottom Ill and containing a stop cock I8 operated by the lever I3 in order to control the sand passage I4.

In the frusto-conical chamber I5, there pene- 15 ytrates axially a conical nozzle I9 connected to the compressed air pipe 8 while there is applied to the opposite frusto-conical wall a frusto-conical nozzle or duct 20 which inwardly contracts the section of this end of frusto-conical cham- 20 ber I5. A exible pipe 2l, through which the stream of sand passes, extends from the outer end of the nozzle 2D.

As Figure 2 shows, the outer end of the nozzle I9 is positioned approximately in the axis 25 of the passage I4, so as to be situated slightly on the side and at the commencement of the maximum opening of the frusto-conical chamber I5. Consequently the stream of compressed air escaping from the nozzle I9 produces at the 30 base of the passage I4, when the latter is uncovered by the stop cock I8, a depression causing the sand to fall regularly into the mixing chamber I5, without provocating therein air eddies and whirls, which are prejudicial to a nor- 35 mal working of the sand blast apparatus. Moreover the air owing out from the nozzle I9 expands in the mixing chamber I5, thus giving to the sand and air mixture a homogeneousness, which is maintained to the delivery pipe 2l 40 owing to the fact that the duct 20 constricts the cross sectional area of this end of the chamber I5.

Finally the deposit of sand in the bottom oi the mixing chamber I5 is prevented by shaping 45 the part I5 thereof tangentially to the divergent air stream escaping from the nozzle I9.

For working, the operator removes the handle I2 yfrom the off position A to the working position M (Figure 1) so as the compressed air 50 comes at the same time in the pipe 5 to lift up the valve 4 and in the pipe 8 to enter the mixing chamber I5 in order to be mixed with the sand escaping from the receptacle 2.

vIi' the passage I4 of said receptacle is ob- 55 structed, it may be easily cleared as follows: after closing the cock I8, the handle I2 is removed in the position E (Figure 1) in which the compressed air is sent only into the mixing chamber I5, and the cover 23 of a curved tube 22 terminating in said chamber above the passage I4 is taken off. By opening then the cock I8, compressed air is suddenly sent into the passage I4 so that the obstruction materials are thrown back out of the receptacle 2 by means of the tube 22.

In order to avoid when the three-Way cock 6 is wholly closed that the air remaining in the receptacle 2 and mixed with dust passes inthe pipe 5 and from there in the cock 6 by Wearing out the same, compressed air escapes by the pipe II and ows directly into the pipe 8 without traversing the cock 6.

I claim:

20 In a sand blast apparatus, a sand receptacle vQllrposite the air nozzle, adelivery pipeextending from said duct, the inner end of said duct being situated said mixing chamber at the point where divergent air stream escaping from the air nozzle reaches the inner Wall of the mixing chamber, the lower part of said mixing chamber being made tangent tothe said divergent air stream. f

EMILE LAUFFER. 

